Help Etch primer peeling??

Discussion in 'Tech Tips' started by edwardo, Mar 6, 2021.

  1. edwardo

    edwardo Well-Known Member Contributing Member

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    Hi all, any paint wizards wanna help a brother out?

    Been prepping my tank for paint. Stripped two layers of old paint and bog down to bare metal.

    Sprayed 2 very light coats of etch and then smashed on some primer filler.

    I have touched up some areas of bog and had sanded back down to metal and noticed my paper had gummed up and that I could scratch off the etch primer with a finger nail with barely any pressure.

    I have had similar issues with etch before. I hate to undo all my work but if the etch is compromised then I'm going to strip it all back down to metal and start again.

    Btw I have been careful with prep and followed correct instructions on the can. What a crock lol
     
  2. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Gumming up on the paper suggests to me it was still slightly wet i.e. not fully dry - time between coats?
    The solvent in the filler primer penetrating the etch primer and needing more drytime

    if you've got a heat gun you could go across it at a gentle heat too much and it will bubble - @my67xr is a painting guru
     
  3. edwardo

    edwardo Well-Known Member Contributing Member

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    Cheers for the input! It had been left for a week so it should have been dry. I'll hit it with some sandpaper tomorrow and see what happens.
     
  4. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Painting was something which almost always flummoxed me - sometimes it worked, sometimes it didn't

    Just thinking out aloud was the dry time of the original etch primer and primer filler sufficient?
    I've seen the paint booths with the infrared light to dry layers on parts being painted, but always suspected that was for workflow speed

    Annoying to have to potentially start again, but if the etch primer is compromised, I suppose the upside is you know now not after you've done the whole thing up to final clear to find out - been there done that with pearl metallics a very long time ago, then there were the pinholes from rust in the tank - start all over again
     
  5. jmw76

    jmw76 Well-Known Member

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    Painting and welding. Both black magic.
    I am a master of neither.
     
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  6. DannoXYZ

    DannoXYZ Well-Known Member

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    Not all primers are equivalent. What brand/model etching primer did you use?
     
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  7. edwardo

    edwardo Well-Known Member Contributing Member

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    Rattle can septone, meant to be better than cheaper options but apparently not haha
     
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  8. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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  9. edwardo

    edwardo Well-Known Member Contributing Member

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  10. DannoXYZ

    DannoXYZ Well-Known Member

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    Depending upon bare metal, there's also surface treatments needed to optimise paint adhesion:

    - sand surface with 300-grit sandpaper
    - degrease with acetone
    - aluminium needs nitric & hydroflouric acid treatment at this stage
    - use zinc-chromate etching primer
    - then filler primer
     
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  11. edwardo

    edwardo Well-Known Member Contributing Member

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    I hit it with 240, wax and greaser remover then 2x light coats of etch. Not sure what etch I had.

    I had a check before and it seems to be holding well now, weird. Maybe solvent leaching into the etch from the primer as mentioned?

    Just gonna go with the black magic Dark arts idea. Maybe I'm too ignorant to learn haha
     
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  12. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    If your local Automotive Paint store is any good.. they should be able to tell you the best way to paint what you want...
    Personally for first coats over bare metal... I would use Thinners or Acetone rather than wax and grease remover, then go with your Etch Primer. Follow the instructions and try to use the same make / type of paint all the way through.
    If it is UPol then have them mix up whatever colour you want and ask them for the right clearcoat... ALWAYS use 2 Pac on your fuel tank as Single pac clear isnt resistant to fuel..
    Good that you are giving it a go... at worst all you will do is spend some $$ and have a crap paint job... alternatively you can end up with a killer paint job... even with Rattle cans.
     
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